# Guangzhou subtropical forest belowground biomass, Model 1 (DBH only)

Root biomass equation for Subtropical evergreen broadleaf forest trees (Castanopsis fissa, Aleurites montana, Castanopsis chinensis, Machilus chinensis and 22 companion species), China, from Zhao et al. 2019. 116 trees. Listed on Tree Allometrics, a free library of tree allometric equations, each quoted from the source that published it.

Fitted on Castanopsis fissa, Aleurites montana, Castanopsis chinensis, Machilus chinensis, and other species the source does not name here.

## Equation

As printed in Zhao et al. 2019 (Section 2.4, Eq. 1):

> ln(B) = a + bln(DBH²)

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#equation

In this library's units, ready to compute (root biomass in kg):

```
Root biomass = exp(-3.151 + 1.111 * ln(D^2))
```

Inputs: D = Diameter at breast height (1.3 m) (cm).
The source's own form: exp(-3.151 + 1.111 * ln(DBH^2)), with DBH in cm; output in kg.
Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#canonical

## What it covers

- Output: Root biomass, kg
- Taxon: Subtropical evergreen broadleaf forest trees (Castanopsis fissa, Aleurites montana, Castanopsis chinensis, Machilus chinensis and 22 companion species) (mixed species); broadleaf
- Where: Fushan, about 26 km northeast of Guangzhou, Guangdong. Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#where
- Biomes: subtropical
- Stand: natural
- Trees measured: 116. Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#n_trees
- R²: 0.914. Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#r2
- Method: ln-ln regression (R, nlme). Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#method
- Verification: read in the original source
- Last checked: 2026-11-02. Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#checked_at

A missing fit statistic is one the source doesn't state, or that we haven't recorded; it is never estimated. Outside the stated DBH range or region, the equation is an extrapolation.

## Source

Zhao, H., Li, Z., Zhou, G., Qiu, Z., & Wu, Z. (2019). Site-Specific Allometric Models for Prediction of Above- and Belowground Biomass of Subtropical Forests in Guangzhou, Southern China. Forests, 10(10), 862.

- DOI: https://doi.org/10.3390/f10100862
- Access: open access
- Copy we read: https://www.mdpi.com/1999-4907/10/10/862/pdf?version=1571725313
- Every equation from this source: https://treeallometry.org/sources/zhao-2019/
- Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#source

## The facts, in the source's words

**Equation** (Section 2.4, Eq. 1):

> ln(B) = a + bln(DBH²)

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#equation

**Equation** (Table 3, Belowground):

> (1) −3.151 ± 0.159 1.111 ± 0.027 0.341 0.914 19.5 38.49 −5.84

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#quote-expression

**R²** (Table 3, Belowground):

> (1) −3.151 ± 0.159 1.111 ± 0.027 0.341 0.914 19.5 38.49 −5.84

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#quote-fit-r2

**Trees measured** (Section 2.2):

> for a total of 116 trees, including 24 species and 7 diameter classes

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#quote-fit-n-trees

**Our note:** ln(B) = a + bln(DBH²). Fitted in R (nlme) on ln-transformed biomass; the paper states no back-transform correction factor and none is applied. Aboveground biomass is above a 10 cm stump (stem, branches, leaves); belowground is the root system plus stump. The paper lists five models (1)-(5); model (2) (ln DBH²H) and (4) (ln DBH²WD) are not added here. The diameter range of the belowground subsample is not stated, so none is given.

## Checks this equation passes

On every build, the library's form and the source's own form (in its units) must both give these values within 1%.

| Inputs | Expected | We get | From |
| --- | --- | --- | --- |
| D = 15 | 17.6 | 17.6 | Computed from the printed form: hand-computed from the published form |
| D = 40 | 155 | 155 | Computed from the printed form: hand-computed from the published form |

Cite: https://treeallometry.org/equations/zhao-2019-bgb-model1/#checks

The calculator on the page shows carbon as biomass × 0.47 (IPCC 2006 Guidelines, Vol. 4, Ch. 4, Table 4.3) and CO₂e as carbon × 44/12.

## How to cite

Cite the source for the equation: Zhao, H., Li, Z., Zhou, G., Qiu, Z., & Wu, Z. (2019). Site-Specific Allometric Models for Prediction of Above- and Belowground Biomass of Subtropical Forests in Guangzhou, Southern China. Forests, 10(10), 862. https://doi.org/10.3390/f10100862

Cite this page for the record and checks: Tree Allometrics (Restoration Scope), "Guangzhou subtropical forest belowground biomass, Model 1 (DBH only)", checked 2026-11-02, https://treeallometry.org/equations/zhao-2019-bgb-model1/. Data CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Quotes are the authors' words.

Data for this equation: https://treeallometry.org/data/equations/zhao-2019-bgb-model1.json
Report a problem: email info@restorationscope.com with the equation id (zhao-2019-bgb-model1) and where the right value appears.